US4070148A - Apparatus for monitoring product temperature in an open ended, secondary emission, product carrying conveyor furnace - Google Patents

Apparatus for monitoring product temperature in an open ended, secondary emission, product carrying conveyor furnace Download PDF

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Publication number
US4070148A
US4070148A US05/695,604 US69560476A US4070148A US 4070148 A US4070148 A US 4070148A US 69560476 A US69560476 A US 69560476A US 4070148 A US4070148 A US 4070148A
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United States
Prior art keywords
furnace
temperature
open ended
cable
product
Prior art date
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Expired - Lifetime
Application number
US05/695,604
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English (en)
Inventor
Frank John Campagna
Gary Frank Pavlovic
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International Business Machines Corp
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International Business Machines Corp
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Filing date
Publication date
Application filed by International Business Machines Corp filed Critical International Business Machines Corp
Priority to US05/695,604 priority Critical patent/US4070148A/en
Priority to JP6129977A priority patent/JPS52153265A/ja
Application granted granted Critical
Publication of US4070148A publication Critical patent/US4070148A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/30—Details, accessories or equipment specially adapted for furnaces of these types
    • F27B9/40—Arrangements of controlling or monitoring devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/02—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity of multiple-track type; of multiple-chamber type; Combinations of furnaces
    • F27B9/021—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity of multiple-track type; of multiple-chamber type; Combinations of furnaces having two or more parallel tracks
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/14—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment
    • F27B9/20—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a substantially straight path
    • F27B9/24—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a substantially straight path being carried by a conveyor
    • F27B9/243—Endless-strand conveyor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D21/00—Arrangement of monitoring devices; Arrangement of safety devices
    • F27D21/0014—Devices for monitoring temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/06—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity heated without contact between combustion gases and charge; electrically heated
    • F27B9/08—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity heated without contact between combustion gases and charge; electrically heated heated through chamber walls
    • F27B9/082—Muffle furnaces
    • F27B9/084—Muffle furnaces the muffle being fixed and in a single piece
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D5/00—Supports, screens or the like for the charge within the furnace

Definitions

  • the present invention relates to apparatus for monitoring product temperature in a furnace, and more particularly relates to apparatus for monitoring product temperature in an open ended furnace of the secondary emission type; the furnace having a plurality of serially arranged heating zones therein and a conveyor which passes therethrough for carrying product thereon through the furnace; the apparatus being located to permit adjustment of the temperature in the various zones of the furnace.
  • gas panels gas discharge display panels
  • process steps which are deemed critical to the final acceptable operation of the panel.
  • a pair of glass plates are processed first by putting a layer of chromium-copper-chromium on one major surface of each of the plates, and then by suitable photo-resist techniques well known in the semiconductor art, the metal is etched to form conductive lines on the plates, the lines on one of the plates being orthogonal to the lines on the other of the plates when they are mated together.
  • the surface of the plates are covered with a passivating layer, for example a glass frit, which is then allowed to be reflowed in a furnace, and which is followed by the laying down of a layer of magnesium oxide.
  • Spacer rods are then placed on the bottom plate along with outboard seal rods along the periphery of the bottom plate, the plates are placed together and then passed through a seal furnace.
  • the seal rods have a lower melting temperature than the smaller diameter spacer rods so that upon the product in the furnace reaching a suitable temperature the sealing rods melt allowing the upper plate to drop down onto the spacer rods thereby forming a pocket or cavity between the two plates which are now sealed around their periphery.
  • the sealing temperature of the rods is critical and must be controlled within very narrow limits.
  • the window for the seal of the type utilized in U.S. Patent application, Ser. No. 572,036, filed on Apr. 28, 1975, now U.S. Pat. No. 3,982,918 should be between 478° to 492° C. If the seal rod does not attain at least 478° C an improper seal will be made, while if the temperature exceeds 492° C crazing of the passivating layers will occur. Accordingly, it is imperative that the temperature of the furnace in which the sealing occurs be very accurately controlled.
  • the panel After a proper cooling off period, the panel is placed in another furnace, a vacuum drawn on a nipple attached to the rear panel, and the panel is permitted to bake under controlled conditions to effect outgassing thereof.
  • the cavity is then filled with a neon-argon mixture and a resistance type heater element around the nipple effects seal off.
  • existing open ended furnaces of the secondary emission type having a plurality of serially arranged heating zones may be brought to their proper operating temperature precisely within a matter of hours as opposed to days, and may be maintained in a clean atmosphere without over reactions in temperature gradients due to drafts.
  • Yet another object of the present invention is to provide a simple yet effective modification for existing furnaces of the type described which permits of easy change of temperature sensors within the muffle of the furnace without shutting down the furnace.
  • Still another object of the present invention is to provide temperature monitoring within the muffle of an open ended furnace which permits of precise zone temperature control even with the furnace in a clean atmosphere.
  • FIG. 1 is a fragmentary side elevation view of a typical furnace incorporating the apparatus of the present invention
  • FIG. 2 is a schematic diagram of a typical set-up for monitoring the temperatures in the various zones of the furnace
  • FIG. 3 is an enlarged sectional view taken along line 3--3 of FIG. 1;
  • FIG. 4 is an enlarged fragmentary perspective view of a typical temperature sensor for use in the present invention.
  • FIG. 1 a typical 14 zone furnace 10 such as manufactured by B.T.U. or Watkins-Johnson is illustrated therein.
  • the furnace has an open inlet end 11 and outlet end 12 and contains a plurality of serially arranged heating zones therein, there being separate heater elements 13 in each zone so as to make the temperature in each zone adjustable even though adjacent zones are in communication with each other.
  • the furnace contains an outer casing 15, adjacent insulating fire brick 16 which form a cavity 17 in the central portion of the casing.
  • Heater elements 13 may also be mounted in the exhaust plenums 18 of blowers 19, the exhaust plenums 18, illustrated in FIG. 1, being connected to the cavity 17 associated with a particular zone.
  • a conventional muffle 20 which receives heat from the heaters (in the illustrated instance electrical heaters) and which heats the product 21 carried on a conveyor, in the illustrated instance, a pair of conveyors 22 and 23 respectively.
  • the panels 21 are located intermediate a platen 24 and a flat cover plate 25 on which a weight 26 is mounted to aid in the sealing process described heretofore.
  • the conveyors 22 and 23 pass through the furnace 10 to permit loading of product 21 at one end and unloading of product from the other end.
  • the conveyor as illustrated, has drive means 27 which permit adjustment of the speed of the conveyor so as to permit adjustment of resident time of product in the furnace.
  • a control panel 28 includes separate controls for each of the zones, for example, when the furnace is heated electrically (as shown), the furnace controls may be comprised of rheostats.
  • the temperature sensor holder comprises a cable 30, in the present instance, fastened at one end to the muffle as at 31 by any convenient means, for example, a hook eye, with the opposite end of the cable passing over a pulley system 32 and connected to a weight 33, the weight serving to maintain tension on the cable and inhibiting sag therein despite the heat of the furnace.
  • the cable may be comprised of a 0.032 inch diameter stainless steel.
  • the temperature sensors may comprise thermocouples such as the type K thermocouples made by Omega Engineering Corporation in Stamford, Connecticut.
  • the thermocouple is mounted in a two-bore tube composed of quartz, the first bore 34 permits the passage of stainless steel wire 35 which is wire wrapped around the stainless cable 30, and the second bore 36 containing a thermocouple such as heretofore described.
  • the wire lead 37 emanating from the thermocouple (wire pair) may be loosely wrapped around the cable and extend to one end 11 or the othe end 12 of the furnace where it is coupled to a small signal amplifier means 38 which may be connected in a conventional manner to a chart recorder, analog readout, etc.
  • the amplifier 38 may be a Rosemount Temperature Transmitter, a Leeds and Northrup amplifier or transmitter, either of which sends an analog signal to either a recorder, or direct reading instrument as above described or to a digital readout system or display to indicate temperature in a particular zone directly.
  • the temperature sensors may be located in any desired position, for example, in FIG. 3, two cables 30A and 30B are illustrated, one directly over each of the conveyors, and additional temperature sensor holding means or cables may be provided at other locations to give a cross sectional temperature gradient within the muffle along any desired plane.
  • the monitoring means 38 may be directly connected to a distributive interface such as disclosed in U.S. Patent application, Ser. No. 673,011, filed on Apr. 2, 1976, the pertinent parts of which are herein incorporated by reference.
  • the distributive interface 39 (FIG. 2) may be connected to a computer 40 such as an IBM System 7 which compares through suitable programming the temperatures actually received from the temperature control monitor in the various zones of the furnace with an ideal temperature profile for the furnace. Any differences in the actual reading verses that which it should be may suitably be displaced on a graphic terminal 41 such as a Tektronix Model No.
  • the operator may make suitable adjustments as through the control rheostat 28. Additionally, if the temperature sensors indicate that a particular critical zone has overheated, to save product within the furnace, the conveyor speed may be adjusted by the operator to limit the resident time of the product within the furnace.
  • the insertion or removal of the cable 30 with associated sensors is relatively simple even with the furnace in operation.
  • a fixture is placed on the conveyor and the cable is attached, the fixture of course having a height sufficient to prevent the cable from touching the product.
  • the apparatus of the present invention permits of the simple modifications of a furnace to monitor the temperature in the various zones so that the product, in the particular instance a gas panel, may be processed in accordance with the known and desired parameters.
  • the cable which is used as the temperature sensor holder of course may be replaced with rods, and of course may be tensioned in many various ways such as by drums which will permit paying in and out of the cable so that the sensors may be more easily removed from the furnace for change or repair.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Tunnel Furnaces (AREA)
  • Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
US05/695,604 1976-06-14 1976-06-14 Apparatus for monitoring product temperature in an open ended, secondary emission, product carrying conveyor furnace Expired - Lifetime US4070148A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US05/695,604 US4070148A (en) 1976-06-14 1976-06-14 Apparatus for monitoring product temperature in an open ended, secondary emission, product carrying conveyor furnace
JP6129977A JPS52153265A (en) 1976-06-14 1977-05-27 Furnace temperature monitor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US05/695,604 US4070148A (en) 1976-06-14 1976-06-14 Apparatus for monitoring product temperature in an open ended, secondary emission, product carrying conveyor furnace

Publications (1)

Publication Number Publication Date
US4070148A true US4070148A (en) 1978-01-24

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US (1) US4070148A (enrdf_load_stackoverflow)
JP (1) JPS52153265A (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2499231A1 (fr) * 1981-02-03 1982-08-06 Pol Ovenbouw Bv V D Dispositif de reglage de la temperature dans un four
US6520675B1 (en) 1998-02-27 2003-02-18 Electronic Controls Design, Inc. Method and apparatus for profiling a conveyor oven
US20160097593A1 (en) * 2013-05-08 2016-04-07 Sandvik Materials Technology Deutschland Gmbh Conveyor furnace
CN109990837A (zh) * 2019-04-12 2019-07-09 马鞍山市科泰电气科技有限公司 一种冷轧锌鼻子的监控方法

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1230035A (en) * 1916-08-09 1917-06-12 Thomas Royston Thermometer-support.
US2646681A (en) * 1950-04-18 1953-07-28 Shell Dev Automatic temperature indicating system
US2712241A (en) * 1952-06-03 1955-07-05 Alfred P D Stokes Automatic instrument positioning and control apparatus
US3247364A (en) * 1962-08-29 1966-04-19 United States Steel Corp Apparatus for measuring temperature differences
US3582054A (en) * 1969-06-04 1971-06-01 Btu Eng Corp Furnace muffle
US3806309A (en) * 1971-12-22 1974-04-23 British Iron Steel Research Temperature measurement

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1230035A (en) * 1916-08-09 1917-06-12 Thomas Royston Thermometer-support.
US2646681A (en) * 1950-04-18 1953-07-28 Shell Dev Automatic temperature indicating system
US2712241A (en) * 1952-06-03 1955-07-05 Alfred P D Stokes Automatic instrument positioning and control apparatus
US3247364A (en) * 1962-08-29 1966-04-19 United States Steel Corp Apparatus for measuring temperature differences
US3582054A (en) * 1969-06-04 1971-06-01 Btu Eng Corp Furnace muffle
US3806309A (en) * 1971-12-22 1974-04-23 British Iron Steel Research Temperature measurement

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2499231A1 (fr) * 1981-02-03 1982-08-06 Pol Ovenbouw Bv V D Dispositif de reglage de la temperature dans un four
US6520675B1 (en) 1998-02-27 2003-02-18 Electronic Controls Design, Inc. Method and apparatus for profiling a conveyor oven
US20160097593A1 (en) * 2013-05-08 2016-04-07 Sandvik Materials Technology Deutschland Gmbh Conveyor furnace
US10480860B2 (en) * 2013-05-08 2019-11-19 Sandvik Materials Technology Deutschland Gmbh Conveyor furnace
CN109990837A (zh) * 2019-04-12 2019-07-09 马鞍山市科泰电气科技有限公司 一种冷轧锌鼻子的监控方法

Also Published As

Publication number Publication date
JPS6119907B2 (enrdf_load_stackoverflow) 1986-05-20
JPS52153265A (en) 1977-12-20

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